I suggest you ...

Enable the use of Azure App Service Certificate with Azure Application Gateway

Today, you have to manage your certificate yourself and provide to Azure Application Gateway a .pfx file.
It would be great if we can have in Azure Application Gateway the same integration we have between Azure App Service and Azure App Service Certificate in order to handle the purchase, renewal, configuration and security of our certificates.
As far as I know, the ASC team has done a seperate Resource Provider and it might be easy to integrate it with other services such as Azure Application Gateway.

This is very important. Since we need to use the App Service Certificate at the Application Gateway, we are forced to turn off auto-renew on the certificate and do it manually. This is a noticeable loss of value to the ASC offering. Allowing the Application Gateway to get the certificate from Azure Key Vault would maintain full functionality.